Understanding the Interface Reactions of Rutile TiO 2 Grown by Atomic Layer Deposition on Oxidized Ruthenium

Abstract

The atomic layer deposition of titanium oxide TiO 2 on ruthenium and oxidized ruthenium with titaniummethoxide as metal precursor and H 2 O and O 3 as oxidant was investigated by Rutherford backscattering (RBS) and time of flight secondary ion mass spectrometry (TOFSIMS). An ultra-thin layer of TiO 2 deposited a priori with H 2 O plays the role of protection of Ru(O x ) substrates against etching by O 3 . Information about thin films (∼3 nm) interfacial reactions, thickness and structure was brought by Medium Energy Ion Scattering Spectroscopy (MEIS) and X-ray absorption spectroscopy (XAS) measurements. The growth enhancements observed in the first stages of the deposition depends on the pre-treatment (pre-oxidation, H 2 O based interlayer thickness) of the Ru substrate. Thick films (∼14 nm) were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The as deposited TiO 2 films are crystalline with rutile structure, as resulted from structural analyzes. However, the presence of small amounts of anatase was detected by soft X-ray absorption spectroscopy (XAS) and is strongly influenced by the surface pre-treatment of the Ru substrate. The electrical properties (equivalent oxide thickness and leakage current density) correlate with a different rutile/anatase ratio present in the films. © 2012 The Electrochemical Society.